Resilient surface coverings, in particular, floor coverings, are widely used. Although they are constructed to have varying degrees of flexibility, they are “resilient” when compared to conventional natural materials, such as ceramic tile.
Chemical embossing has been used to create surface coverings with a desired three-dimensional appearance. Chemical embossing typically involves applying a foamable layer to a substrate, where a foaming agent, inhibitor and/or promoter is applied in a pattern. The foamable layer is subjected to conditions that cause foaming only to occur in selected regions, which regions are in register with the pattern.
Many surface coverings include a wear layer in addition to the chemically embossed foam layer. The wear layer can also include a top coat. The prior art generally teaches chemically embossing a foamable layer, applying a wear layer, and then curing the wear layer. From a processing standpoint, it would be advantageous to be able to cure the wear layer while the foamable layer is being cured. However, a limitation associated with curing the foamable layer and the wear layer at the same time is that if the wear layer is too rigid, the chemical embossing is restricted. If the wear layer is too flexible, the stain resistance and wear properties such as scratch resistance of the wear layer are reduced.
From an environmental standpoint, it is desirable to apply coating compositions to substrates using either one hundred percent solids coating compositions or waterborne coating compositions, to minimize the use of organic solvents. The one hundred percent solids coating compositions typically include photocurable resins, such as acrylates. These are not typically cured with heat, but rather, by irradiation.
Accordingly, it would be desirable from both a processing and an environmental standpoint to have waterborne coating compositions that cure with heat in conjunction with foamable layers that expand and cure with heat. It would also be desirable to have waterborne coating compositions that are rigid enough to provide suitable stain resistance and wear resistance, but that are flexible enough that a foamable layer can be chemically embossed while the coating layer is cured. The present invention provides such a waterborne coating composition.